Alkaline treatment of coffee

ABSTRACT

Ground, roasted coffee or spent coffee grounds are treated with an alkaline material to provide coffee extract in increased yield and with improved color.

United States Patent Ye-ransian [54] ALKALINE TREATMENT OF COFFEE [72]Inventor: James A. Yeransian, Pearl River, NY.

[73] Assignee: General Foods Corporation, White Plains,

22 Filed: Sept.25, 1969 21 Appl.No.: 861,140

[52] US. Cl ..99/71 [51] Int. Cl. ..A23i 1/08 [58] Field ofSearch..99/71 [56] References Cited UNITED STATES PATENTS 2,036,345 4/1936Merkel ..99/71 2,712,501 7/1955 Hale et a1 ..99/71 5] Feb. 22, 19722,573,406 10/1951 Clough et a1 ..99/7l 3,155,523 11/1964 Reich ..99/7lOTHER PUBLICATIONS Sivetz, Coffee Processing Technology, Vol. 2, 1963pages 240-242.

Primary Examiner-Frank W. Lutter Assistant Examiner-William L. MentlikAtt0rneyGerald E. Jacobs, Bruno P. Struzzi and Thomas V. Sullivan [57]ABSTRACT Ground, roasted coffee or spent coffee grounds are treated withan alkaline material to provide coffee extract in increased yield andwith improved color.

8 Claims, No Drawings ALKALINE TREATMENT OF COFFEE BACKGROUND OF THEINVENTION This invention pertains to alkaline treatment of coffeeextract and roasted and ground coffee being extracted to produce asoluble coffee with darker color and/or to obtain increased percolationyields.

Ground roasted coffee is generally extracted with water at a temperaturein the range of from about 50 C. to about 230 C. The extraction may becarried out in one or more extraction columns in series. For economicconsiderations, it is desirable to maximize the yield of soluble solids.It is also desirable to obtain a dark colored product.

The preparation of instant or soluble coffee starts with ground, roastedcoffee which is treated with water until from about percent by weight toabout 35 percent by weight of the fresh roasted bean is extracted aswater-soluble solids. It has been known to carry out this process in thepresence of sulfuric acid or phosphoric acid. The acid-treated coffeeextract is subsequently neutralized, care being taken to insure that thepH does not exceed 7.0 during or subsequent to neutralization. Priorextraction techniques, however, fail to maximize the yield of solublecoffee solids, or to obtain a product as dark in color as possible.

SUMMARY OF THE INVENTION It has now been found that an increased yieldof soluble solids and a darker colored product are obtained bycontacting a coffee material with an alkaline material. The coffeematerial may be ground roasted coffee which is contacted with analkaline material during extraction or prior to drying the coffeeextract, or the coffee material may be spent or ex tracted coffeegrounds which are contacted with an alkaline material. In the case ofground roasted coffee, an alkaline material may be added to the feedwater used to extract the ground coffee, or to the final extractioncolumn, or to any intermediate point. The coffee extract may becontacted with alkaline material just prior to drying. In the case ofspent coffee grounds, the alkaline material may be added to spent coffeegrounds or to blow down liquor.

The invention is directed to a method for treating a coffee materialwhich comprises contacting a coffee material with an alkaline material,the contacting taking place in an aqueous medium at a temperature aboveabout 50 C., the concentration of alkaline material being at least about0.01 N.

The invention is directed to a method for treating a coffee materialwhich comprises contacting a coffee material with an alkaline material,the contacting taking place in an aqueous medium at a temperature of atleast about 85 C., the concentration of alkaline material being at leastabout 0.025 N.

The invention is directed to a method for treating a coffee materialwith an alkaline material, the contacting taking place in an aqueousmedium at a temperature in the range of from above about 50 C. to about275 C., the concentration of alkaline material being at least about 0.01N.

The invention is directed to a method for treating a coffee materialwhich comprises contacting a coffee material with an alkaline material,the contacting taking place in an aqueous medium at a temperature offrom about 85 C. to about 200 C., the concentration of alkaline materialbeing at least about 0.025 N.

The invention is directed to a method for treating a coffee materialwhich comprises contacting a coffee material with an alkaline material,the contacting taking place in an aqueous medium at a temperature offrom about l50 C. to about 180 C., the concentration of alkalinematerial being at least about 0.025 N.

The invention is directed to a method for treating a coffee materialwhich comprises contacting a coffee material with ammonia, or thehydroxides, carbonates or the bicarbonates of the alkali metals, thealkaline earth metals, or mixtures thereof, in an aqueous medium at atemperature in the range of from above about 50 C. to about 275 C., theconcentration of alkaline material being at least about 0.01 N.

The invention is directed to a method for treating a coffee materialwhich comprises contacting a coffee material with ammonia, thecontacting taking place in an aqueous medium at a temperature aboveabout 50 C., the concentration of ammonia being at least about 0.025 N.

The invention is directed to a soluble extract of coffee obtained bytreating a coffee material with an aqueous solution, the concentrationof alkali being at least about 0.01 N, the extract having a high and lowmolecular weight fraction, the high molecular weight fraction having amolecular weight as determined by the Sephadex procedure of about 50,000or higher acid hydrolysis of the purified high molecular weightfraction, followed by treatment with an ion exchange resin yields afirst component comprising amino acids, a second component comprisingneutral compounds, and a third component comprising organic acids. Thelow molecular weight fraction is similar to the organic acids componentof the high molecular weight fraction.

DETAILED DESCRIPTION The alkaline material may be ammonia, or thehydroxides, carbonates or bicarbonates of the alkali metals, or of thealkaline earth metals, or mixtures thereof. In addition, two or morealkaline materials may be employed sequentially.

The treatment of a coffee material by an alkaline material is affectedby the particular alkaline material chosen, its concentration, thetemperature at which the treatment is carried out and, the length oftime for which the treatment is continued. The conditions which maximizeyield of soluble solids are not necessarily the same as those whichyield the darkest color.

The yield of soluble solids depends mainly upon temperature andconcentration of base. As a practical matter, the solution of alkalinematerial should be at least about 0.01 N and the temperature should beabove about 50 C. Preferably, the solution of alkaline material shouldbe at least about 0.025 N and the temperature should be at least aboutC. More highly concentrated alkaline solutions may, of course, be used.In fact, the amount of alkaline material may exceed the amount of coffeematerial. The yield of soluble solids in creases as the concentration ofalkaline material increases. At lower concentrations of alkalinematerial (up to about 0.002 parts by weight), the yield is moredependent upon temperature than time of extraction. At higherconcentrations of alkaline material, time and temperature are of lessinfluence than concentration. The extraction time may vary from a fewminutes to several hours. Generally, however, the treatment with analkaline material according to the present invention will last at leastabout 10 minutes.

The coffee material may be treated with an alkaline material accordingto the present invention at temperatures of from about 50 C. up to about275 C. Preferably, however, the temperature is from about 85 C. to about200 C. Most preferably, the temperature is from about C. to about 180 C.

The alkaline material may be added as a solid, or as a solution or as aslurry. Ammonia is a preferred alkaline material as it may be removed byboiling after treating the coffee, leaving no residual cations. When acation-containing alkaline material is employed, excess cations may beremoved by any conventional method, for example, by treatment with anion exchange resin, by acid precipitation, by alcohol precipitation, orby dialysis of the soluble extract.

The use of an alkaline material to treat coffee material provides anincreased yield of soluble coffee product as well as a darker product.The extract obtained by treating the coffee material with ammonia, orammonium hydroxide, however, is noticeably darker than that obtained bytreatment with a strong base, such as, for example, sodium hydroxide.Extraction with ammonia gives a product having a color about 2 or 3times as great as is obtained with a strong base. For this reason, andbecause it can be removed simply by heating, ammonia is a preferredalkaline material.

Better results are obtained in some cases by treating the spent coffeegrounds sequentially with a plurality of alkaline materials, forexample, first with ammonia and then with sodium hydroxide or,alternatively, first with sodium hydroxide and then with ammonia.

The product resulting from the alkaline treatment is a dark coloredextract which may be treated in numerous ways. For example, it may befiltered, neutralized, and treated with an ion exchange material toyield a dark colored liquid extract which may be added to the liquidextract resulting from the initial extraction of the roasted coffee.

The extract resulting from the alkaline treatment of the spent groundsmay be dried to yield water soluble, caramel colored solids which arerelatively bland tasting and can be blended with the soluble coffeepreviously obtained in percolation.

The extract resulting from the alkaline treated spent coffee grounds maybe neutralized, and treated to remove cations if the alkaline materialused is not ammonia, to obtain an extract free of materials formed fromthe fat fraction of the coffee. This extract may be added to the liquidextract resulting from the initial extraction of the roasted coffee.

By adding coffee flavor and aroma to the dried extract resulting fromthe alkaline treatment of the spent grounds, a reconstitutible coffeedrink powder is obtained.

The alkaline treatment of a coffee material according to the presentinvention produces a product which is distinctly different from thatobtained by aqueous extraction or aqueous acidic extraction of coffeematerial. The product obtained by treating a coffee material with analkaline material has a high molecular weight fraction and a lowmolecular weight fraction. The high molecular weight fraction has amolecular weight determined by the Sephadex procedure of about 50,000 orhigher. Acid hydrolysis of the purified high molecular weight fractionfollowed by treatment with an ion exchange resin separates the highmolecular weight fraction into three components. The first componentcomprises amino acids, the second component comprises neutral compounds,probably monosaccharides, and the third component comprises organicacids. The low molecular weight fraction is similar to the organic acidscomponent of the high molecular weight fraction.

The following examples illustrate the present invention without,however, limiting the same thereto.

EXAMPLE I Six runs were made in each of which 50.0 grams of spendgrounds were placed in 500 ml. of water and extracted with ammoniumhydroxide for 1 hour at the concentration and temperature shown for eachrun. The yield of soluble solids is expressed as percent by weight.

Saturation maintained with gaseous ammoniav EXAMPLE ll Six runs weremade in each of which 50 grams of defatted spent grounds were added to500 ml. of water and extracted with sodium hydroxide at 100 C at theconcentration and time shown for each run. The yield of soluble solidsis expressed as percent by weight.

RUN CONC. NuOH TlMF. YIELD l 1 gram l hr. 6% 2 2 grumn l hr. 9%

3 5 grams 1 hr. 24% 4 10 grams l hr. 34% 5 20 grams l hr. 44% 6 5 gramsl 5 hr. 31%

EXAMPLE Ill The following runs show the effect of temperature and timeupon the solubilization of defatted spent coffee grounds. Each run used50 grams of spent grounds in 500 ml. of water. Yield is expressed aspercent by weight.

A most important effect of temperature is to degrade the solublematerial into fragments. The degree of fragmentation is criticallydependent upon temperature. At temperatures greater than approximately200 C., the soluble extract is fragmented to such a degree thatundesirable flavors and aromas are produced. A balance between maximumyield and minimum degeneration of the soluble product is achieved attemperatures in the range of from about 150 C. to about l C.

What is claimed is:

1. A method for treating spent coffee grounds in order to increase theiryield comprising the steps of:

a. obtaining spent coffee grounds from a soluble coffee process;

b. contacting the spent grounds with an alkaline material, thecontacting taking place in an aqueous medium at a temperature aboveabout C, at a concentration of alkaline material of at least about 0.025N, and lasting at least about 10 minutes;

c. treating the extract resulting from the alkaline treatment of thespent grounds in order to remove excess cations; and

d. drying the treated extract to yield water soluble solids.

2. A method according to claim 1 wherein the alkaline material isselected from the group consisting of ammonia, the hydroxides,carbonates and bicarbonates of the alkali metals and alkaline earthmetals, and mixtures thereof.

3. A method according to claim 1 wherein the water soluble solids areblended with soluble coffee solids obtained from said soluble coffeeprocess.

4. A method according to claim 1 wherein the treated extract is added tothe liquid extract obtained from said soluble coffee process beforedrying.

5. A method according to claim 1 wherein coffee flavor and aroma isadded to said water soluble solids.

6. A method according to claim 1 wherein the spent grounds aresequentially contacted with a plurality of alkaline materials.

7. A method according to claim 6 wherein ammonia is one of the alkalinematerials.

8. A method for producing soluble coffee, said method producing anincreased yield of soluble solids and a darker soluble productcomprising the steps of:

a. extracting roast and ground coffee with an alkaline ammonia material,the extraction taking place in an aqueous medium at a temperature aboveabout 85 C. and at an ammonium ion concentration of at least about 0.025N;

b. boiling and resulting aqueous extract to remove residual 5 ammoniumions; and then 0. drying the aqueous extract.

2. A method according to claim 1 wherein the alkaline material isselected from the group consisting of ammonia, the hydroxides,carbonates and bicarbonates of the alkali metals and alkaline earthmetals, and mixtures thereof.
 3. A method according to claim 1 whereinthe water soluble solids are blended with soluble coffee solids obtainedfrom said soluble coffee process.
 4. A method according to claim 1wherein the treated extract is added to the liquid extract obtained fromsaid soluble coffee process before drying.
 5. A method according toclaim 1 wherein coffee flavor and aroma is added to said water solublesolids.
 6. A method according to claim 1 wherein the spent grounds aresequentially contacted with a plurality of alkaline materials.
 7. Amethod according to claim 6 wherein ammonia is one of the alkalinematerials.
 8. A method for producing soluble coffee, said methodproducing an increased yield of soluble solids and a darker solubleproduct comprising the steps of: a. extracting roast and ground coffeewith an alkaline ammonia material, the extraction taking place in anaqueous medium at a temperature above about 85* C. and at an ammoniumion concentration of at least about 0.025 N; b. boiling and resultingaqueous extract to remove residual ammonium ions; and then c. drying theaqueous extract.